The Concupiscence Conjectures. (Or, Roy Mustang and Riza Hawkeye's very scientific theorem on making out.) With hypotheses to be proven and a summer to spare, Riza and Roy steal moments to themselves between their studies to work on their bonds. Part of The Soldier's Element Series. [Young Royai]

At some point she had scooted onto his bed, and they'd put aside the books he was supposed to be studying in favor of more adventurous pursuits. It wasn't the first time they'd snuck a small exchange of kisses between his study breaks, but before they'd mostly been cut short. But this time, Riza had prolonged it a little longer, brushing her lips against the corner of his mouth before he adjusted to deepen their kiss. Leaning against his headboard, she had twined her arms around his neck and drawn her legs up to her chest, continuing their kiss eagerly.

Everything seemed to be working quite nicely, and though she wasn't quite sure about his tongue's placement, the way his hands slid over her waist was nice enough to merit a pleased hum from the back of her throat. Maybe kissing with tongues was just something she'd get used to. Roy seemed like he might know about these sorts of things, and while they'd tried it once or twice before, it had always ended after she pointed out he should probably get back to studying.

This time, Riza didn't feel particularly eager to get him to refocus on what he was supposed to be doing. So when Roy interrupted their kiss first, she was rather surprised. She opened amber eyes with a quizzical look, peering back at him as he leaned back on his knees on the bed, eyeing her up and down thoughtfully.

"You seem a little tense." Roy said, not appearing upset, but she could still hear the concern in his voice. It was a question, more than anything. Riza looked back at him, and shook her head firmly.

"I'm fine." she answered, brushing back her bangs behind her ears.

"You're sort of curled up in a little ball, and your shoulders are tensed up." Roy pointed out, and Riza self-consciously dropped her shoulders. She hadn't been thinking about it while she was doing it. Roy didn't say anything else, but it was clear by the look in his sharp eyes that he was expecting some sort of communication.

Riza sighed. "Have you ever done this before?"

Roy blinked, as if taken aback by the question, and then swallowed. "Um, which part?"

"This kind of kissing, and the…other stuff." Riza said, suddenly feeling awkward for having brought it up. It really wasn't her business, and she'd never particularly worried or even cared about any other girls he might have had kissed, but it still seemed obvious that at almost eighteen, maybe Roy knew a little something she didn't. Her wealth of experiences was mostly limited to him. "I haven't done this with anyone else." she clarified a little lamely.

This seemed to cause Roy's eyes to widen slightly. At least now he got what she was getting at. His hand went up to rub the back of his neck like he did whenever he felt awkward, or embarrassed, and Riza bit her lip to keep from smiling. It was rather endearing to watch him whenever he did that.

"It's—I mean it's not something I've done a whole lot of. I was busy. Studying." Like he should have been doing right now. Roy raised a brow, giving her that silly half-smirk he always gave when he was being too confident about something. "It can't be too different from a scientific experiment, can it?" Roy asked, clearing his throat. "If the results aren't satisfactory, change the parameters of the experiment."

"And if the experiment fails?" Riza asked pointedly.

Roy shrugged. "No such thing as a failure. Just a new set of data to work off of. If you don't like anything, we can stop." he assured, leaning back towards her with a smile. Riza grinned in kind, rolling her shoulders as leaned back to press her spine back into his headboard.

"Do you have a hypothesis to work off of, Mister Mustang?" She said with a cheeky grin of her own.

"Sort of." Roy said quietly, his eyes dropping as he chewed his lip and gazed at the spot where her skirts rode up over her knees. They were still drawn up against her chest, and Roy kneeled before her causing Riza's face to flush in realization that he did have a plan of some sort. And before she could worry about what that was, Roy gave her another half-smile that made his eyes seem too black, and that gave her a funny - but pleasant - turn in her stomach.

"Do you mind if I kiss your knees?" He said softly, and Riza snapped her chin up, giving him a look.

"My knees?" Riza said in surprise. She moved to grab his bedsheets, fisting her hands into his blanket before she gave him another confused look. It seemed like such an odd request, but Roy seemed to think it was perfectly normal. (But then, he'd just admitted he didn't have half the idea she thought he did.)

"Like this," Roy motioned, sliding a hand under her calf, running his hand up until he hit the crook of her knee, and kissed the top of the spot where her skirt hem hit her legs. Riza gasped in surprise, that was nice, and let him slide her leg out; relaxing her sitting position. Roy's lips slid down to her calf, working down to kiss her ankles in a light sort of way that caused her to squirm in her seat before he switched legs, and worked his way back up to her skirts.

She didn't realize she had been holding her breath as he lingered at her knees until Roy looked up again. "Alright?" Roy asked pleasantly.

Riza nodded. "Satisfactory." she said, trying to collect herself as calmly as she could. Roy smiled proudly before he moved again, reaching for one of her hands knotted in his bed sheet, and fitting his hand over hers. She laced their fingers together in response, slipping her palm against his. He brought her knuckles to his lips, and kissed them gently before he moved to position himself so that her legs were on either side of him. Roy held back a small distance, as if testing her new boundaries, and Riza leaned up, resuming her placement of a hand around his neck.

Leaning forwards, Roy moved her leg again, hooking his hand under her knee as he began to kiss her again. Admittedly, Riza thought, the access was a bit nicer now that she wasn't blocking the broadness of his chest with her legs tucked up nearly to her chin. It certainly made the kissing more enjoyable, and Riza was quite certain her shoulders were no longer hunched up. Roy's tongue swiped along the bottom of her lip, causing her mouth to tingle, and Riza wriggled to pull him closer to her.

This seemed to cause a positive reaction in Roy, and he made a deep rumble in his throat that was encouraging. Riza's tongue darted out, and she repeated the same thing he had done just moments ago, before running her tongue over the roof of his mouth. He leaned into her a little more heavily, and Riza reminded herself that smiling smugly while kissing would probably not be very beneficial. Instead, she hooked one of her legs over his encouraging the new level of comfort. This was starting to get easier as it went along.

At some point between her moving, and his kissing, Roy's hands had moved from her waist to the tie under her peter pan collar, fumbling with the knotting for a few moments before it started to unravel in his fingers. Breaking their kiss, Riza looked up and rose a brow. Roy's fingers hovered where they were, the crisp blue ribbon in his hands. He flushed under her scrutinization, before awkwardly placing the ribbon on the bed beside her hips. Riza bit her lip for a moment, stifling a giggle.

"Uh…" Roy explained.

Riza wanted to look back down at her knees, but found herself looking at the buckle on Roy's belt, sliver and glistening against his black slacks. Somehow, that didn't seem to help her blushing a brilliant shade of pink. After a moment's silence, Riza cleared her throat, and slipped her fingers over the top button at her collar. Roy blinked, watching her with fascination. "My shirt, right?" she said, popping the buttons free from their holes.

"If that's alright." Roy said, the apple of his throat bobbing slightly as he swallowed nervously. Riza sucked in a breath, popping her bottom lip back into her mouth before she nodded distinctly. It seemed fine, at any rate, and Roy's hands were so nice on her waist that she thought his hands going elsewhere would probably be nicer. She stopped three buttons down, not quite sure what else to do before Roy leaned back in, his black hair tickling the underside of her chin as he kissed her exposed collarbone hesitantly.

Scientific method. Testing his theory was simply a part of that. Roy's fingers looped the other buttons out of their holes, exposing the top of her chest and then the smooth lines of her belly that moved as she breathed in. Riza ran her palm up to the base of his skull and threaded her fingers through his hair gently, as Roy pushed her shirt out of his way. He didn't seem too keen on rushing things, and Riza wondered if it was because he was getting a feel for what he was doing, or if it was because he was being gentlemanly about things. It was hard to tell, and her concentration slipped as he open mouth kissed the top of her breast where her bra ended and the strap began. Riza shifted again, her leg hitching closer to his hips, before she realized exactly how frustrating it was to feel his belt buckle dig into her. Still, she didn't bother to reach for his pants quite yet, thoroughly enjoying the concentration Roy was putting into her chest. It wasn't terribly graceful, but he blew gently over her when he removed his lips, and she shivered, goosebumps prickling her skin.

Then he pulled down the straps of her bra, pulling them down over her shoulders to follow her blouse, not really bothering to unhook the offending garment. Riza's grip on his hair tightened, and whatever words Roy had planned to say seemed to end up as some sort of throaty purring noise instead. Then he tested another kiss on the base of her throat as he palmed her right breast gently.

"Oh." Fingers curling in his hair, Riza tilted back her head as she sighed. "Can you um," She said shakily, licking her lips. "-Just move your hand a little." she directed firmly, noting that she was right about his hands. They were long and slender, and calloused in a few places from what she wasn't sure - but it really felt very nice, and she didn't want him to stop.

"Like this?" Roy asked, brushing his thumb over her nipple curiously as he tried to move just enough to catch her expression. Stifling a squeak, she nodded, before adding somewhat shortly, "A little more."

Fortunately, Roy Mustang was an excellent student. Prodigies were often cocky, natural talent having gone to their head. But fully understanding that Roy was too damned stubborn to just give up when he wasn't perfectly hitting the mark, Riza waited for him to roll her nipple between his fingers, letting him kiss her skin and return that funny burning feeling that nestled low in her body —

— right about where that damn belt buckle kept digging in to her lower belly.

"Unm," Riza gasped, as Roy gently laved his tongue over her other nipple, before moving away to seal his lips over her flesh. "Roy," she said carefully, before peeling his head back off her chest. There was a sudden flush of disappointment on his face, before Riza shook her head. "Roy, your belt. It's digging into me." She said slowly.

"Could you take that off? The latch sort of sticks out, and it's really starting to hurt the longer you lean on me like that."

"Oh, uh - Riza I don't…I don't think that's the latch." Roy stumbled, blinking a few times rapidly before he leaned back a little to reach for his belt. Stunned, he fumbled with it for a few long moments before finally getting the metal to unhook.

"It was the belt that was bothering me." Riza said quietly, as she clarified. She dipped her head down, before she remembered she was finding herself nearly face to face with the waistband of his pants. Hooking a finger through his belt loop, she averted her eyes from Roy's crotch and slowly took in the rest of him.

It was no big secret that now she hardly had much composure to speak of; what with her shirt and bra half off and her skirts rucked up from how he'd been leaning into her. But looking at Roy made it hard not to laugh, because if she was in a state of sorts, he seemed to be much worse off. And his pants did look distinctly tighter than they had been before, and Riza sort of pitied the lack of help removing the belt had done for him. Eventually, she realized, they would probably have to do something about that.

"Your shirt. You should probably take it off." Riza said pointedly, moving her hands to the bottom of his shirt. She freed his buttons to expose him at his waistband and then his stomach, flat and beginning to be defined from exercise. At first she had thought his jogging at obscene hours of the morning and his insistence on pushups while he read alchemy texts were a bit ridiculous, but now she had to admit it was rather nice to admire the results.

Roy moved to help her with the top buttons of his shirt, loosening the collar before he pulled the whole thing half undone over his head and discarded it by tossing the shirt onto the floor. "Better?"

"Much." she declared with an impish smile. "Where were we…?"

Roy rolled his shoulders, tilting his chin towards her chest, before trying delicately to place himself back where he had been resting before, appearing somewhat awkward as he tried to manage his growing erection. A blonde brow raised up as Riza moved to unhook her bra entirely and toss it onto the floor as well beside Roy's shirt. As Roy sunk further into his mattress with a groan, he propped himself up, and Riza fought to keep from making another smart comment about his predicament.

In typical Mustang generosity - under all that bravado - he sunk his chin into the spot between her breasts and looked up at her with an expression that made her stomach do another turn. It was affectionate, in a way Riza didn't quite expect, but devious in another that made all too much sense.

They shifted again, Roy's arm bracing on the other side while Riza opened her mouth to say something about the state of his expression. But instead of words, a loud clatter startled them both, and Riza looked around the room in search of its source.

"What was…?" She asked sharply, ears straining to catch another noise, a shift of her father's chair or the clicking noise his study door made when he finally bothered to unlock it and haunt the places of the house outside of that room.

"I don't-" Roy stumbled carefully before he leaned over the side of his bed. "Oh. That."

She closed her eyes in frustration as she realized he'd knocked his alchemy books to the floor. "My father might've heard that." She warned, snatching her blouse from the floor, buttoning it half way before the tucked the ends of her shirt into her skirt's waistband. Adjusting her collar, she gave a frustrated sigh as she realized there was nothing to be done about the fact that she was probably a shade of bright pink, and her hair was mussed, and worst of all, her clothes were rumpled and you could probably smell Roy's aftershave all over her. Her father would just have to take one look at them both to decide to serve up apprentice en flambé for dinner.

Which would be rather unfortunate.

Pouting, Roy watched her scramble to leave. Normally he tried to wheedle her into staying another minute more. This time, however, it was a little different. He stood up before her, and she leaned up on slight tiptoes to kiss his cheek and then his mouth quickly in gratitude. "That was nice. Thank you. But…"

"You should get going before your dad wonders why books are falling from shelves." Roy filled in helpfully with a mournful look.

"Exactly. Until you have another long study break…" Riza said, before opening his door, and ducking out of his room quickly. Her skirts flared around the edge of his door before she shut it behind her with a quick click.

"Wait," Roy said a moment later, as he looked down to the ribbon in his hands. "-you forgot your tie." Realizing she hadn't heard him, Roy shrugged, and pocketed it. He'd give it back next time, when she noticed it was missing.

This work is already complete, and will be updated once weekly. The summer of 1903 places Riza at the age of sixteen and Roy at the age of eighteen, for those who wondered. Reviews appreciated. Thanks for reading.

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